I nternational FireS afety S ymposium 2015

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Proceedings of the

International Fire Safety

Symposium 2015

Coimbra, 20-22 April, 2015

Portugal

Hot Disk

®

Organizers:

cib - International Council for Research and Innovation in Building Construction

UC - University of Coimbra

albrasci - Luso-Brazilian Association for Fire Safety

Editors:

João Paulo C. Rodrigues George V. Hadjisophocleous Luís M. Laím

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Proceedings of the

International Fire Safety Symposium 2015

Organizers:

CIB - International Council for Research and Innovation in Building Construction UC - University of Coimbra ALBRASCI - Luso-Brazilian Association for Fire Safety

Authors:

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Proceedings of the International Fire Safety Symposium 2015

held at the Department of Civil Engineering of the University of Coimbra, Portugal 20th_-22nd_{April 2015}

ISBN 978-989-98435-5-4 ISSN 2412-2629

A Simposium organised by

International Council

for Research and Innovation in Building and Construction (www.cibworld.nl)

University of Coimbra (www.uc.pt)

ALBRASCI

Luso-Brazilian Association for Fire Safety

(http://www.albrasci.com)

All rights reserved. No part of the publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopied, recording or otherwise, without prior permission of the Publisher.

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Organizing Committee

João Paulo Correia Rodrigues, UC - University of Coimbra, Portugal (Chairman)

Greg Baker, BRANZ, New Zealand (Co-chairman)

Cristina Calmeiro dos Santos, UC - University of Coimbra, Portugal C.J. Walsh, Sustainable Design International ltd., Ireland

Ehab Zalok, Carleton University, Canada

Hélder David da Silva Craveiro, UC - University of Coimbra, Portugal Hugo Caetano, UC - University of Coimbra, Portugal

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Scientific Committee

George V. Hadjisophocleous, University of Carleton, Canada (Chairman)

Ahmed Kashef, National Research Council, Canada Ali Nadjai, University of Ulster, UK

Brian Meacham, WPI, USA

Charlie Fleishman, University of Canterbury, New Zealand Dhionis Dhima, CSTB, France

Ehab Zalok, Carleton University, Canada Euripidis Mistakidis, University of Volos, Greece

Frantisek Wald, Technical University of Prague, Czech Republic George Boustras, European University of Cyprus, Cyprus Geraldine Charreau, INTI, Argentina

Gintaris Kaklauskas, Technical University of Vilnius, Lithuania Gordon Andrews, University of Leeds, UK

Guillermo Rein, Imperial College of London, UK Guo-Qiang Li, Tonngji University, China Jean Marc Franssen, Liège University, Belgium

João Paulo Correia Rodrigues, University of Coimbra, Portugal Jose Torero, The University of Queensland, Australia

Juan de Dios Rivera , Pontificia Universidad Católica de Chile Karen Boyce, University of Ulster, UK

Kathrin Grewolls, Ingenieurbüro Für Brandschutz Grewolls, Germany Manfred Korzen, BAM, Germany

Manuel Romero, Universidad Politecnica de Valencia, Spain Maria Cruz Alonso – Instituto Eduardo Torroja, Spain Paulo Vila Real, University of Aveiro, Portugal Pierre Pimienta, CSTB, France

Pietro Gambarova, Politecnico de Milano, Italy Raffaele Landolfo, University of Naples, Italy

Ricardo Cruz Hernandez, Universidad de Santander, Colombia Rita Fahy, National Fire Protection Association, USA

Rosária Ono, University of São Paulo (School of Architecture), Brazil Simo Hostikka, VTT, Finland

Sunil K. Sharma, Fire Research, Central Building Research Institute, India Takashi Horiguchi, University of Hokkaido, Japan

Tan Kang Hai, Nanyang Technological University, Singapore Ulf Wickstrom, Lulea University of Technology, Sweden Ulrich Krause, University of Magdeburg, Germany

Valdir Pignatta e Silva, University of São Paulo (School of Engineering), Brazil Venkatesh Kodur, Michigan State University, USA

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PREFACE

On behalf of the Organising and Scientific committees, as well as the CIB W-14 Commission on Fire Safety it is our pleasure to welcome you to the International Fire Safety Symposium - IFireSS 2015, which is organised by the CIB’s Commission W14-Fire Safety, ALBRASCI and University of Coimbra. The Symposium aims to contribute to the exchange of ideas and knowledge in the area of Fire Safety and assist in planning future research activities in this area. CIB W14-Fire Safety is a Working Commission of CIB (International Council for Research and Innovation in Building & Construction) and its main objectives are:

• To create an ongoing research and innovation focus for the development of a comprehensive, coherent, rational and empirical basis for a safe and sustainable built environment, which includes fire science and engineering practices and design methodologies; • To promote the acceptance of Fire Science and Engineering Practices, Procedures and Design Methodologies worldwide, and to encourage their use in Building and Fire Safety Legislation, Codes, Regulations and Standards;

• To provide technical input, from a Fire Science and Engineering Perspective, to other relevant CIB Working Commissions and Task Groups;

• To facilitate the transfer of state-of-the-art Fire Science and Engineering Technology at international level;

• To encourage capacity building for Fire Science and Engineering worldwide.

The Luso-Brazilian Association for Fire Safety (ALBRASCI) was established recently by Portuguese and Brazilian specialists in the area of Fire Safety to create a platform for the development of Fire Safety in Portugal and Brazil.

The University of Coimbra (UC) is a reference in higher education and research in Portugal, due to the quality of the courses taught and to the advances achieved in pure and applied research in various areas of knowledge. UC is also well-known around the World due to the research and training in Fire Safety with an MSc and PhD in the area.

The Symposium has participants from researchers around the world and covers a wide variety of research areas including: Structural Fire Safety; Mechanical and Thermal Properties of Materials; Fire Chemistry, Physics and Combustion; Fire Reaction; Fire Safety in Vehicles and Tunnels; Fire Risk Assessment; Smoke Control Systems; Firefighting and Evacuation; and Fire Regulations, Standardization and Construction Trends.

Joao Paulo C Rodrigues George Hadjisophocleous

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IFireSS – International Fire Safety Symposium

Coimbra, Portugal, 20

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nd

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FIRE BEHAVIOUR OF LIGHTWEIGHT CONCRETE UNITS BASED ON

CORN COB AGGREGATE

Nuno Alves

Civil Engineer UTAD – Vila Real

Portugal

Paulo Piloto

Professor IPB – Bragança

Portugal

Elza Fonseca Professor IPB – Bragança

Portugal

Luísa Barreira

Mechanical Engineer IPB – Bragança

Portugal

Débora Ferreira

Professor IPB – Bragança

Portugal

Jorge Pinto

Professor UTAD – Vila Real

Portugal

ABSTRACT

Recent research works have concluded that corn cob may have interesting material properties, in particular, lightness, and thermal and sound insulation abilities. In this research work, corn cob is proposed as an alternative sustainable aggregate for lightweight concrete masonry unit (CMU) manufacturing. The corn cob requires to be granulated previously in order to obtain adequate particle size grade. Subsequently, the particles are wrapped in a cement paste with the purpose of reducing their water abortion and adherent capacities. CMU are current applied in the building of partition walls. The main goal of this research work consists on studying the fire behaviour of partition walls built with CMU of processed corn cob granulate (CMU-PCC).

Keywords: Lightweight concrete unit; corn cob aggregate, organic material; masonry; sustainable construction; fire.

1. INTRODUCTION

The search for alternative environmental friendly building solutions has been the goal of the scientific and the technical communities. Affordable, low energy and good quality water

consumptions, and small amount of CO2 emission into the atmosphere are important attributes

that these solutions have to fulfil. In general, applying organic products as raw building materials may be a step forward to achieve these attributes because they are likely of being abundant,

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local and renewable. For instance, rice husk ash blended cement has been proposed as a partial substitute of cement in mortar production [1].

On the other hand, corn cob has also been proposed as an alternative aggregate for the manufacturing of lightweight concrete for non-structural applications [2]. In these cases, there is an additional advantage because these organic products are treated as agricultural waste [3].

In this research work, lightweight concrete unit based on processed granulate of corn cob (CMU-PCC) is proposed as an alternative building material. In this case, processed granulate of corn cob (PCC) works as a substitute of current applied lightweight aggregates such as expanded clay (EC).

For the manufacturing process of CMU-PCC it was adopted geometrical and size typologies, composition and manufacturing technology similar to the ones currently applied in CMU based on expanded clay (CMU-EC). Therefore, this type of unit (CMU-EC) was used as reference in this study.

Taking into account that partition walls are a potential building scenario in terms of the application of the CMU-PCC, the respective fire behaviour is fundamental to know. Thus, the main goal of this research work consists on giving a contribution in this context by performing an experimental and a numerical preliminary analysis of the proposed building material under specific fire conditions.

Samples of CMU-PCC and CMU-EC were tested under fire conditions related to the standard fire curve indicated in ISO 834 [4]. The obtained experimental results allow understanding the behaviour of the units under severe fire conditions. In addition, these results are also used to validate a numerical model of the fire behaviour of these units.

This paper is structured as follows: firstly, a brief description of the CMU-PCC is done; secondly, the adopted set-up of the fire test is explained; thirdly, the fire behaviour numerical analysis is introduced; fourthly, the main results are presented and discussed; finally, some conclusions are drafted.

2. LIGHTWEIGHT CONCRETE UNIT BASED ON PROCESSED GRANULATE OF CORN COB (CMU-PCC)

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(which their LWA is EC) were prepared according to the following proportion in terms of weight 1:1.02:1.22:2.04:0.76:0.88 (C/C:MS/C:LS/C:G/C:LWA/C:W/C) and 1:1.15:1.38:2.31:0.87:1 (C/C:MS/C:LS/C:G/C:LWA/C:W/C), respectively.

CMU were prepared considering the standard dimensions 500 mm × 200 mm × 200 mm (length (L) × width (W) × height (H)) with a +3/-5 mm dimensional tolerance.

After the manufacturing process, the dimensions, the dry mass (mdry,s) and the bulk density (ρ)

of CMU were assessed. The average (AVG), the standard deviation (SD) and the coefficient of variation (CoV) of these measures are presented in Table 1.

Table 1: Dimensions, dry mass and bulk density of the studied CMU

L (mm) W (mm) H (mm) mdry,s (kg) ρ (kg/m3)

CMU-EC

AVG 497 201 199 11.494 1364

SD 1.19 1.03 1.16 0.716 41

CoV (%) 0.24 0.51 0.58 6.23 3.0

CMU-PCC AVG SD 0.62 496 0.49 200 1.57 197 14.081 0.778 1748 60

CoV (%) 0.12 0.24 0.79 5.52 3.5

3. FIRE TEST

At this preliminary research stage, the reduced number of samples available CMU-EC and CMU-PCC was a testing limitation. Therefore, it was necessary to simplify the test set-up prescribed for masonries in EN 1364-1 [5]. Thus, in both cases (i.e. masonry wall of CMU-EC and masonry wall of CMU-PCC), it was only possible to build a masonry wall with two CMU. Figure 1.a shows the case of CMU-PCC masonry wall sample. Another adopted testing procedure simplification is related to the fact that the masonry wall samples were tested in the horizontal position. Only the upper surface of each masonry wall samples has to be exposed to fire. The other surfaces of the samples were protected with fibreglass panels, according to Figure 1.

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Figure 2) were also placed at the intermediate hollows of the CMU. The temperatures measured by T and TP sensors will be used to validate the proposed numerical study (i.e. masonry wall of CMU-EC and masonry wall of CMU-PCC) in Section 4.

Figure 1: CMU-PCC masonry wall sample. Left: Thermocouple application, Right: Lateral fire protection

a) Plan view (mm) b) Sections A-A and B-B

Figure 2: Schematic representation of the location of the thermocouple sensors

The fire tests were performed using a fire resistance furnace existing at Polytechnic Institute of Bragança (Bragança, Portugal), Figures 1 and 3. This equipment is able to carry out the ISO 834 standard fire curve test.

B

A

B

TP1

TP2 T5 T14 T6 T4 T3 T2 T1

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Figure 3: Fire test performance (Left: during test, Right: after testing)

In order to evaluate the fire insulation ability of a wall, the temperature evolution on the unexposed surface was assessed (TD sensors are used for this purpose). In that surface, two criteria are necessary to verify. The first criterion consists on guarantying that there is not an average temperature increasing of 140ºC (related to the initial average temperature of that building element, TD0). Meanwhile, the second criterion consists on ensuring that an increasing

of temperature up to 180ºC (related to the initial average temperatureof that building element,

TD0) does not occur in any point of that surface of the wall.

TD0 is the average value of the temperatures measured by each TD sensor at the beginning of the test. In the cases of CMU-EC and CMU-PCC masonry wall samples, the quantified TD0 was 26ºC and 22ºC, respectively.

4. NUMERICAL MODELING OF THE FIRE BEHAVIOUR OF CMU-EC AND CMU-PCC

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Figure 4: Finite element mesh of the CMU masonry wall samples (built with 2 CMU)

The temperature-dependent material properties of CMU under research are unknown. In particular, the thermal conductivity and the specific heat capacity of CMU-PCC. However, Eurocode 6 [7] presents data of these material properties for lightweight aggregate concrete units with a density range of 600 – 1000 kg/m3. Therefore, based on several numerical simulations and based on the experimental data (in particular, TP temperature measuring), it was possible to estimate the temperature-dependent material properties of CMU under research (CMU-EC and CMU-PCC). These material properties are indicated in Figure 5. In addition, the considered emissivity value was 0.87 which is related to cement based mortars.

Figure 5: Temperature-dependent material properties of CMU-EC and CMU-PCC

The considered boundary conditions were convection and radiation in the exposed surface to fire and in the hollows, respectively, [8]. It was numerically assumed that the temperature evolution of the surface of the wall exposed to fire was similar to the respective curve of ISO 834. On the other hand, in the hollows of the CMU, the respective temperature evolution was based on the experimental measurements of TP (from TP1 to TP4, Figure 2.b). It was also adopted a convection coefficient equal to 25 W/m2K and a fire emissivity equal to 1.

Laying joint _{Surface exposed to fire}

0 7 14 21

0 200 400 600 800 1000 1200

T, [ºC]

Calor específico [kJ/kgK] Massa volúmica x100 [kg/m^3] Condutividade térmica [W/mK]

Thermal conductivity [W/mK] Density x100 [kg/m^3]

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5. RESULTS PRESENTATION AND DISCUSSION

In both cases (CMU-EC and CMU-PCC masonry wall fire tests), there was acceptable concordance between experimental and ISO 834 fire curves (“Real forno” and ISO 834 curves in Figure 6) and according to [9]. At the same time, the temperature measurements by TP are also presented in Figure 6 (curves TP_e). These TP_e curves allow us understanding the temperature evolution of the walls during the fire test performance and also the fire behaviour of each element. As expected, in both cases, the upper part of the wall (related to TP1 and TP3, Figure 2.b) presented higher temperature than the lower part of the wall (related to TP2 and TP4, Figure 2.b). There was also a good agreement between TP1_e and TP3_e curves in both cases, Figures 6.a and 6.b. In contrast, there was a certain discrepancy between the measurements of TP2_e and TP4_e (Figure 6.a and 6.b). This fact may be justified considering the adopted simplified fire insulation of the wall.

a) CMU-EC wall sample b) CMU-PCC wall sample

Figure 6: Real and ISO 834 fire curves. TP curves (Note: “e” means experimental; “Real forno” means real furnace; “seg” means second)

In order to complement the above information, Figures 7.a and 7.b present the temperature curves (TD_e) related to the measurements of the five TD placed on the surface unexposed to fire (Figure 2.a) of the CMU-EC and the CMU-PCC wall samples, respectively. For each case, the average temperature curve (TDmedia_e) and the numerical temperature curve (TD_n) are also plotted in Figure 7.

In both cases, the second criterion has failed. As a result, CMU-EC and CMU-PCC masonry wall samples have shown a fire resistance of 83 minutes and 72 minutes, respectively. At the same time, in both cases, the wall samples also kept their structural integrity during the fire test. Therefore, both building elements have shown similar fire resistance behaviour which let us concluding that the standard CMU-EC and the alternative CMU-PCC may be adequate for partition walls concerning fire resistance ability.

0 200 400 600 800 1000

0 600 1200 1800 2400 3000 3600 4200 4800 T [ºC]

t [seg]

Real Forno ISO 834 TP1_e TP2_e TP3_e TP4_e

0 200 400 600 800 1000

0 500 1000 1500 2000 2500 3000 3500 4000 4500 T [ºC]

t [seg]

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Figure 7: Temperature evolution of the surface unexposed to fire. Experimental (e) and numerical (n) values. (Note: TDmedia_e corresponds to the average value of the measurements

of TD; “seg” means second)

The verified acceptable concordance between TDmedia_e and TD_n curves for CMU-EC and CMU_PCC walls (Figures 7.a and 7.b, respectively) may allow us validating the proposed numerical model of the fire behaviour of each wall under research. The data presented in Figure 8 also give strength for this validation.

Figure 8: Temperature in certain parts of the wall (experimental (e) and numerical (n))

6. FINAL REMARKS

The fire resistance of CMU-PCC was evaluated in this research work. At each stage of this study, CMU-PCC was compared to CMU-EC which is a current applied lightweight concrete masonry unit for partition walls.

In both cases, similar fire behaviour was verified. That fire behaviour was adequate and the materials have shown appropriate fire resistance after being under the exposure of the ISO 834

0 50 100 150 200 250 300

0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200

T [ºC]

t [seg]

TD1_e TD2_e TD3_e TD4_e TD5_e TDmedia_e TD_n

0 50 100 150 200 250 300

0 500 1000 1500 2000 2500 3000 3500 4000 4500

T [ºC]

t [seg]

TD1_e TD2_e TD3_e TD4_e TD5_e TDmedia_e TD_n

0 200 400 600 800 1000

0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200

T [ºC]

t [seg]

T12_e T10_e T9_e

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fire curve during 60 minutes. This fact, may indicate that the application of processed granulate of corn cob as a lightweight aggregate may be promising.

A fire behaviour numerical model of CMU was also defined and proposed in this research work. The concordance between experimental and numerical values was acceptable. This numerical model has shown appropriate for both CMU-EC and CMU-PCC. The thermal-dependent material properties of these CMU were adjusted by this numerical model. In addition, the proposed numerical model may be useful for studying the fire behaviour of other standard geometrical solutions of CMU.

It is worth to emphasize that this work corresponds to a preliminary stage. A more representative amount of CMU-EC and CMU-PCC wall samples, real size wall samples and testing the wall samples in the vertical position are some technical aspects that require to be considered in further research to be done in this context.

REFERENCES

[1] Ganesan, K., Rajagopal, K. & Thangavel, K. - Rice husk ash blended cement: Assessment

of optimal level of replacement for strength and permeability properties of concrete,

Construction and Building Materials, vol. 22, 2008, p.1675-1683.

[2] Pinto et al. - Corn cob lightweight concrete for non-structural applications – Construction and Building Materials, vol. 34, 2012, p. 346-351.

[3] Pinto et al (2011). Corn`s cob as a potential ecological thermal insulation material. Energy and Buildings. vol. 43, Issue 8, 2011, p. 1985-1990.

[4] ISO 834-1. “Fire-resistance tests - Elements of building construction – Part 1: general requirements”. 1999.

[5] EN1364-1 – Ensayos de Resistencia al fuego de elementos no portantes – Parte 1: Paredes, 1999.

[6] ANSYS Teaching Introductory, Release 15.0, Help System, ANSYS, Inc.

[7] EN1996-1-2: 2005. Eurocode 6: Design of masonry structures - Part 1-2: General rules – structural fire design. CEN – European Committee for Standardization

[8] EN 1991-1-2: 2002. Eurocode 1: Actions on structures. - Part 1-2: General actions – actions on structures exposed to fire. CEN – European Committee for Standardization, 2002.

I nternational FireS afety S ymposium 2015

Proceedings of the

International Fire Safety

Symposium 2015

Coimbra, 20-22 April, 2015

Portugal

Hot Disk

Organizers:

Editors:

Proceedings of the

International Fire Safety Symposium 2015

Organizing Committee

Scientific Committee

PREFACE

CONTENTS

IFireSS – International Fire Safety Symposium

Coimbra, Portugal, 20

_-22

_{April 2015}

FIRE BEHAVIOUR OF LIGHTWEIGHT CONCRETE UNITS BASED ON

CORN COB AGGREGATE

B

A

A

B

albrasci

Luso-Brazilian Association

for Fire Safety

University of Coimbra

Hot Disk

International Council

for Research and Innovation

in

Building and Construction

Institute for Sustainability and Innovation in

Structural Engineering